查看更多>>摘要：Overuse of fossil fuel energy contributes to excessive CO2 emissions into the air,causing a range of environmental problems,which force people to change this situation.The proposal of the"carbon peak"and"carbon neutrality"strategies marked a new level of awareness of CO2 emissions.Utilizing the extensive and sustainable solar energy to transform CO2 into valuable chemicals is a promising avenue.In particular,the solar-assisted i conversion of CO2 into methanol provides an effective method of storing carbon resources,thereby alleviating the environmental problems caused by CO2.In addition,the storage of solar energy in chemical energy could also alleviate the associated energy shortage issue.This review summarizes the latest achievements of catalysts in methanol synthesis from CO2 via photocatalysis,photothermal synergistic catalysis,and photoelectric synergistic catalysis.The advantages and shortages of each category of catalysts are pointed out and the future development perspectives are presented,hopefully facilitating the design and development of relevant photocatalysts.
查看更多>>摘要：Photocatalytic nitrogen fixation from air directly under sunlight can contribute significantly to carbon neutralization.It is an ideal pathway to replace the industrial Haber Bosch process in future.A Fe-doped layered WO3 photocatalyst containing oxygen vacancies was developed which can fix nitrogen from air directly under sunlight at atmospheric pressure.The iron doping enhances the transport efficiency of photogenerated electrons,The photocatalytic efficiency is around 4 times higher than that of pure WO3.The optium nitrogen fixation conditions were examined by orthogonal experiments and its nitrogen fixation performance could reach up to 477 μg·g_(cat)~(-1)·h~(-1)under sunlight.In addition,the process of nitrogen fixation was detected by situ infrared,which confirmed the reliability of nitrogen fixation.Also,modeling on the interactions between light and the photo-catalyst was carried out to study the distribution of surface charge and validate the light absorption of the photocatalyst.This work provides a simple and cheap strategy for photocatalytic nitrogen fixation from air under mild conditions.
查看更多>>摘要：The aim of this study is to develop novel and an efficient bifunctional heterogeneous catalyst based on the SnO2@Mn-ZIF core shell support decorated with Tungstophosphoric acid(TPA)active moieties.The designed catalyst was characterized with Thermal Gravimetric analysis(TGA/DTA),X-Ray Diffraction analysis(XRD),Scanning Electron Microscopy(SEM),Energy Dispersive X-Ray(EDX)analysis,Fourier transform infrared spectroscopy(FT-IR),Brunauer Emmet Teller(BET)analysis and Temperature Programmed Desorption of ammonia(NH3-TPD)and carbon dioxide(CO2-TPD)for structural and morphological investigation.Effect of crucial parameters such as methanol to oil molar ratio,reaction temperature,reaction time,agitation speed and catalyst dosage were thoroughly studied to develop profitable biodiesel process.The results indicated that Tungstophosphoric acid was well dispersed on the surface of the support.Further,it was noted that the catalyst with 30 wt% Tungstophosphoric acid onto the support formulation provided maximum biodiesel yield of 91.5 % under optimum reaction conditions of 6 wt% catalyst dosage with 18:1 methanol to oil molar ratio,500 rpm stirring speed and reaction temperature of 100 ℃ for 3 h.Finally the designed catalyst experienced profound stability and was recycled up to five times for biodiesel production without any prior treatment.
查看更多>>摘要：A type of delaminated MWW zeolite is synthesized in the presence of hexamethyleneimine and dicyclohexyl-amine via a hydrothermal crystallization method.The appropriate molar ratio range of HMI/DCHA is found to correlate with the laminar morphology and crystallinity of the prepared zeolite samples.The delaminated MWW zeolite possesses thinner layered structure,larger external surface area and more accessible active sites than the conventional MCM-22 sample,and its protonated form can be used as a superb catalyst in benzene alkylation with cyclohexene.Under the optimized reaction conditions,the conversion of cyclohexene reaches 99.9 % while the selectivity to the target products,cyclohexylbenzene and dicyclohexylbenzene is 95.4 % in 1000 h lifetime experiment.Because of better diffusion properties and more abundant accessible acid sites on external surface,the delaminated MWW is superior to the conventional MCM-22 in benzene alkylation with cyclohexene,despite of the similar microporous structure and bulk acid properties of these two samples.
查看更多>>摘要：To improve the stability of Pt nanoparticles,the redox cycles with oxidation at 800 ℃ and reduction at 250 ℃ for three times were adopted on the Mn-mullite doped Pt-based catalysts(Pt-YMO/SA-Red)to rearrange the Pt atoms.The light-off temperature toward CO/C3H6/NO oxidation on Pt-YMO/SA-Red decreases by 20-60 ℃,and the NO maximum conversion is improved by 27 % than the catalyst with only oxidation treatment at 800 ℃(Pt-YMO/SA-Oxi).Characterization results verify that the interaction of Pt with YMn2O5 on Pt-YMO/SA-Red is reinforced via redox cyclic treatment to inhibit the aggregation of platinum particles and promote the formation of active oxygen species,in comparison to Pt-YMO/SA-Oxi.The easier active oxygen regeneration and more active platinum sites contribute to the excellent catalytic performances and stability.In addition,the mechanism for the high CO/C3H6/NO oxidation performance are analyzed via the detected reaction intermediate species.
查看更多>>摘要：Herein,we demonstrate that surface acid-base properties have marked effect upon the performance(activity,selectivity and stability)of supported Ru catalysts upon tandem hydrocyclization(hydrogenation-dehydration)of aqueous levulinic acid.A mesoporous bi-functional Ru/NbOPO4/SBA-15 catalyst incorporating highly dispersed Ru sites and well balanced strong Br0nsted acidic sites(optimum B/L and M+S/W ratio)was identified,which outperformed the benchmark monofuncational(Ru/SBA-15,Ru/MCM-41)and physically blended bi-functional catalysts(Ru catalysts mixed with acid co-catalysts e.g.NbOPO4/Amberlyst-15).Further,the catalyst also demonstrated remarkable stability in a fixed-bed reactor,maintaining steady activity and γ-valerolactone selectivity(72-86%)during ca.300 h time on stream(10 bar,90-100 ℃),corroborating its industrial potential.The exceptional performance and durability of the bi-functional catalyst was attributed to the presence of well dispersed hydrothermally and chemically stable acid(NbOPO4)and redox(Ru)sites.
查看更多>>摘要：To improve efficiency of hydrogen production,other anodic reactions with lower theoretical potential like urea oxidation reaction(UOR)to replace OER were explored.Herein,we synthesized FeCo layered double hydroxide(FeCo-LDH)in situ on nickel foam(NF)that had excellent OER and UOR catalytic ability and durability.The good catalytic performance can be attributed to the special crossed nanosheet structured FeCo-LDH with large specific surface area,rapid electron transfer.At the current density of 50 mA cm~(-2),the overpotential is 228 mV during OER,and the voltage value is 1.353 V vs.RHE during UOR.When FeCo-LDH was used as electrocatalyst,the voltages required for water and urea electrolysis to reach the current density of 10 mA cm~(-2)are 1.523 V and 1.409 V,respectively.The strategy of constructing FeCo-LDH on NF plays an important role in high efficiency hydrogen production,and has great application prospects in sustainable energy efficient conversion.
查看更多>>摘要：The metal-free graphitic carbon nitride(g-C3N4)with a series of merits like low cost,favorable stability,and controllable two-dimensional graphite-like structure,has been extensively studied for photocatalytic H2 evolution.Composite engineering is regarded as one of effective strategies to adjust the kinetics of photogenerated carriers in g-C3N4 for elevating its photocatalytic performance.Herein,the composite system of g-C3N4 with oxynitride LaTiO2N was elaborately constructed for improving photocatalytic H2-evolution performance.With systematical characterizations,the partial cover of g-CsN4 nanosheets on LaTiO2N(LaTiO2N@g-C3N4)was verified and promoted the sufficient contact between g-C3N4 and LaTiO2N,accompanied by the formation of the(oxy)nitride heterojunction.Benefited by the well-matched band structures for g-CsN4 and LaTiO2N,the(oxy)nitride heterojunction strengthened the separation of photogenerated carriers and therefore enhanced the photocatalytic performance of g-C3N4.This work gives more insight in composite engineering on g-C3N4,and also provides feasible guidelines for designing g-C3NU-based photocatalysts towards improving photocatalytic performance.
查看更多>>摘要：A new catalytic system for the direct conversion of various amine carbamates into urea derivatives was devised by combining corresponding amine solvents with CeO2 catalyst.The amine solvents suppressed undesired thermal decomposition of amine carbamates,resulting in the high-yielding production of urea derivatives with high turnover frequency(TOF).One of the reactions demonstrated here was the conversion of ethylenediamine carbamate(EDA-CA)in an ethylenediamine(EDA)solvent.This system produced 2-imidazolidinone(62% yield)and N,N'-bis(2-aminoethyl)urea(38% yield,including its related compounds).The TOF based on the catalyst amount for the EDA-CA transformation was 3.7 h,which was at least 6-fold higher than those in previously reported systems operated in different organic solvents at similar reaction temperatures.In the presence of water additive,this catalytic system relying on the CeO2 catalyst and EDA solvent became slower than the reaction without water additive but could still produce the urea derivatives in high yields.
查看更多>>摘要：A single-component synergistic catalytic system,in which multiple active sites act on a substrate with minimal energy input and promote efficient conversion of the substrate,is considered to be the most advanced technology for simulating enzyme catalytic reaction.The design principles of this technology are the driving force behind the pursuit of cost-effectiveness in industrial production,but the challenges remain formidable.Herein,three periodic mesoporous polyamides with triazine-derived networks(PMP-TDNs)were prepared via"one-pot"poly-condensation,and used as non-metallic catalysts for cycloaddition of CO2 with epoxides without any additives to synthesis cyclic carbonates.The composition and physicochemical properties of PMP-TDNs were evaluated via different analytical methods to explore the crucial factors affecting catalytic activity.Especially,the activity of PMP-TDNs-MI with multiple hydrogen bond donor(HBD)and high-density N basic sites have been tested effectually; the results has demonstrated a superior reactivity for the cycloaddition of CO2 and a wide range of epoxides with reusability.The kinetics and thermodynamics of cycloaddition of CO2 with propylene epoxide by PMP-TDNS-MI were investigated,and the cooperative catalytic mechanism between the versatile active sites of catalyst was revealed based on the experimental results.
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